Not applicable
The present invention generally relates to type III-V semiconductor devices, and more particularly to a digitally graded rectifying structure for use in a GaAs semiconductor device.
Gallium arsenide (GAAs) semiconductor devices have several advantages over their silicon counterparts. In particular, GaAs devices exhibit faster and more optimized speed/power performance and efficiency at a low supply voltage of 1 volt and below. In prior art, diodes which contain a potential barrier diodes have been widely used as the detector elements in microwave and milli-meterwave rectifiers, receivers, and imaging systems. Each of these particular devices have limitations in performance and manufacturability. One particular type of low barrier diode, The Schottky Barrier Diode, may be fabricated from either silicon or on compound semiconductor substrates such as GaAs or InP. The barrier height in this type of diode has its barrier height predetermined by the metal-semiconductor barrier. The barrier height is not readily adjustable in the Schottky barrier diode, and the resistance of the diode is not independently adjustable either. In order to obtain microwave diodes with engineered barrier heights, rectifier diodes with n-i-p-i-n junctions and n-p-n junctions have been demonstrated such as those outlined in U.S. Pat. No. 4,410,902. These planar doped barrier semiconductor devices allow for adjustable barrier heights, but are not manufacturable because attomole or femtomole levels of semiconductor dopant must be incorporated into less than 5 angstroms of semiconductor material. The variability in the production of these thin structures with such miniscule levels of dopant is not reproducible by using even the modern methods of Molecular Beam Epitaxy of Metal Organic Chemical Vapor Deposition.
This patent is generally directed towards a method and device for providing a diode structure that has a barrier height that may be readily engineered with a series resistance that may be independently varied while simultaneously providing for the complete characterization and discernment of the barrier height in a microwave and millimeter-wave rectifying diode without the need for device fabrication and electrical measurement. The present invention generally relates to microwave and millimeterwave diodes, and more particularly to low barrier structures within these diodes that are capable of rectification of microwave and millimeterwave radiation. The diode structure comprises a semiconductor substrate, a periodic structure consisting of alternating layers on binary compound semiconductors that exist in crystalline form on said substrate, a doped contact layer with sufficient doping and thickness to provide for the formation of electrical contact with ohmic behavior, a barrier structure consisting of some combination of multiple heterojunctions and alternating layers that may be periodic in nature or of a chirped superlattice nature in said barrier, and a doped contact layer that is of the proper thickness and doping to allow the formation of a sufficient electrical contact with ohmic or partly resistive nature as necessary for the required contact.